This invention relates generally to a passive solar energy storage system for use in conjunction with light transmitting glazing and, more specifically to a modular, phase-change material filled pod unit that can be assembled adjacent to glazing surfaces as partially light transmissive, thermal energy storing arrays.
Conventional building structures utilize various types of glazing to establish desired interior lighting levels. Typically, such glazing structures are thermally inefficient in that they transmit excessive levels of solar radiation to the building interior during certain time periods and provide an undesirably high rate of heat loss from the building during other time periods. Attempts to alleviate this problem with coated or tinted glass, double thicknesses of glass, isolating draperies, etc., offer partial solutions but leave much to be desired.
Previously proposed systems for increasing thermal energy efficiency have included materials that experience a liquid-solid phase change at temperatures substantially above that required to freeze water. When thawed by direct exposure to solar radiation, such materials can absorb a substantial quantity of thermal energy which can be subsequently released. Disclosures of such materials and systems in which they are used appear in the following U.S. Pat. Nos. 4,162,671 (Christy); 4,158,355 (Spitzer); 4,100,091 (Powell); 4,054,125 (Eckels); 4,003,426 (Best et al); 3,960,205 (Laing); 2,595,905 (Telkes) and the following publications: "Passive Solar Collector Wall Incorporating Phase Change", C. R. Hauer, R. V. Remillard, L. D. Nichols, 2nd. Passive Solar Conference, Philadelphia, PA, Mar. 17, 1978; "Passive Solar Energy Collector", C. R. Hauer, R. V. Remillard, L. D. Nichols, Final Report; EIKONIX Corporation, May 3, 1978; "Storage Configurations for Phase Change Materials", George A. Lane, Grey L. Warner, Philip B. Hartwick; Solar Engineering, August, 1979; "Solar Energy Storage", Maria Telkes, ASHRAE Journal, September, 1974. Although offering some advantages, prior phase-change material systems are less than satisfactory either individually or collectively because of numerous deficiencies such as increasing lighting energy costs by totally blocking sunlight, exhibiting poor heat transfer characteristics because of excessive reflection from crystals formed when the phase-change materials freeze, requiring costly custom designs in either geometry or material content, incorporation of materials, exhibiting thermal inefficiencies resulting from uneven and slow freezing and thawing of the phase-change material, etc.
The object of this invention, therefore, is to provide a more efficient, passive solar energy storage system for use in conjunction with the conventional glazing employed in building structures.